1. Field of the Invention
The subject invention generally pertains to refrigerant systems and more specifically to a cascade heat pump system.
2. Description of Related Art
Geothermal heat pump systems often include a refrigerant system that exchanges heat with the ground via a borefield or some other means. A borefield basically is a buried network of pipes through which a fluid is pumped. As the fluid flows through the borefield, the fluid exchanges heat with the surrounding ground, and the refrigerant system then uses the exchanged heat energy to help heat or cool a certain load.
Drawbacks of current geothermal heat pumps include limited operating modes, need for reversible refrigerant circuits, need for selectively operating a heat exchanger as a condenser and an evaporator, and/or unnecessary mixing of relatively high and low temperature fluid. Consequently, there is a need for a better heat pump system that is particularly useful in geothermal applications but also useful for more conventional water source systems.